Tesco is extending its same-day online grocery delivery service across Northern Ireland as it looks to compete with rivals.

The supermarket giant said that the service, currently only available in London and the South East, will now be rolled out across stores here, covering "over 99% of UK households".

In what will be a five-week process, the bigger stores here will initiate the same-day delivery service roll out. These include Newtownbreda, Carrickfergus, Lisnagelvin, Craigavon, Ballymena, Knocknagoney Road and Dungannon.

Over the next four to five weeks Coleraine, Banbridge Bridgewater, Antrim Massereene, Newtownards, Lisburn's Bentrim Road, Newry and Enniskillen will follow suit.

Tesco claimed that the move gives it the "biggest reach of any retailer in the UK, stretching from the Shetland Islands in Scotland to Cornwall in south-west England".

Customers can order by 1pm to have their shopping delivered from 7pm onwards and receive an unlimited number of items, with the new service priced between £3 and £8.

Adrian Letts, managing director of Tesco Online, said: "We've seen the service grow in popularity since we launched it in London and the South East so we're really excited to be rolling it out to customers nationwide."

The move comes following the launch of AmazonFresh, which entered the UK market last year, raising fears that the dominance of the so called Big Four - Tesco, Morrisons, Sainsbury's and Asda - could be further eroded.

Tesco, along with the other established players, has also been hammered by the emergence of discount retailers Aldi and Lidl.